Boss snow plows makes a very nice unit. I have Boss plows on all my trucks, and plan on adding one to one of my machines as well. The 8' is priced right around $2700 assembled and shipped to my door.
I would say you could handle a 7.5 to 8 foot. I can handle a 7.5 on my L3240hstc, so at 45 hp I don't see why you couldn't take a 8 footer.